The present invention relates to a rail engagement apparatus having rail engagement wheels for a road vehicle. More specifically, the rail engagement apparatus is relatively compact in movement. Further, this invention relates to a vehicle having such an apparatus mounted to it.
As used herein, a road vehicle is a vehicle having wheels which contact a highway or other road, as opposed to only having wheels which roll on rails on a railroad track.
Railroad service crews often have to go to various places along a railroad track in order to make repairs and inspections. Depending upon the type of service which is performed and other factors, the service crew may ride to the work site using a rail vehicle or using a road vehicle, such as a truck or car. Since the best way to a work site may include travel along a road and travel along a railway, service crews and other rail workers often have used road vehicle having a rail engagement or guide wheel apparatus mounted on them. Such cars or trucks may travel along a highway or other road with road wheels engaging the road. Upon getting to an appropriate place along the railway, the rail engagement apparatus is operated such that front and back pairs of railway wheels are lowered from the vehicle until the vehicle is bound to the railway. When the operator wants the vehicle to leave the railway, the two front railway wheels and the two rear railway wheels are retracted or lifted up such that the vehicle may again run along the road.
Various structures have been used to allow railway wheels to be attached to road vehicles. Although such structures have been generally useful at moving the railway wheels between an upper position in which the vehicle may travel along a highway or other road and a lower position in which the vehicle travels along a railway, such structures have often been subject to one or more of several disadvantages.
Some prior structures do not always maintain sufficient contact between the rails and the rail wheels. Thus, driving the vehicle faster than is safe may risk derailment upon irregularities in the rails. Many prior structures require a significant clearance zone to allow the rail wheels to move between rail and road positions. Such a clearance zone requirement may limit the type of vehicle on which the equipment is mounted and may limit the mounting position on a particular vehicle. Some such structures require precise vehicle positioning before initially engaging rail wheels with the rails. Slight mispositioning of the vehicle may require that the vehicle be moved using the road wheels before making a second attempt to engage the rail wheels. Some structures may have ability to move relative to the vehicle to which they are mounted for centering, but that ability may be limited in flexibility such as requiring movement of both rail wheels in a pair in the same direction at the same time. Some prior designs use plural controls which require two hands of a human operator or coordinated action by hands of different human operators. Some prior designs may use suspension systems which limit the ground clearance of the vehicle.
The prior U.S. Pat. Nos. 5,154,124, issued Oct. 13, 1992, and 5,186,109, issued Feb. 16, 1993, both in the name of Harry Madison, one of the inventors of the present invention, both assigned to the assignee of the present application, both relate to different rail guide wheel apparatus for moving a highway vehicle along a railroad track. Both of those patents are hereby incorporated by reference.